[R-390] Re: Electrical panels and grounds...

Sun, 5 Jan 2003 12:12:06 -0800

Interesting way to illustrate I squared R...

Like compound interest, exponentials are the eighth wonder of the world. All
the others may be lost in antiquity, but that eighth one keeps rearing its
beautiful head...

Bob

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Kenneth G. Gordon
Sent: Sunday, January 05, 2003 11:41 AM
To: [email protected]
Subject: [R-390] Re: Electrical panels and grounds...

This thread reminds me of a short story Roberta Barmore told us
on the Glowbugs list a while back. She is Chief Engineer at a big
combined AM/FM/TV station in the midwest somewhere, and a
ham.

She was walking by the main three phase panel which fed power to
the entire transmitter site and noticed that it seemed to be
somewhat warm. Then a few evenings later, she thought she saw a
slight reddish glow, so she called an electrician.

He showed up the next day, and after putting down some thick
rubber mats, and removing the panel, crawled back in under the
panel and looked up.

Her words were, "...then he said a very bad word and backed out
slowly..."

Apparently the center one of the very large copper buss bars was
glowing red hot. When the panel was assembled at the factory, the
assembler had misaligned the center buss bar when drilling the
mounting holes in it and had offset it to one side or the other by
quite a distance. There was a very small gap between it and one
next to it. Further, the bolt holes were damaged in such a way that
the bolts couldn't properly clamp the buss bar to its mount, so the
current carrying capability of the buss bar was signifcantly
lessened. So much so that it heated up with the current load and
loosened the bolts, making it hotter yet, and so on.

They had to cut the station power WAY back to keep the panel
from burning up while waiting for the replacement panel.

Ken Gordon W7EKB
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